So many things begin to slow down as a person ages. Usually, people perceive slowing down as a negative. But when it comes to the thyroid, Dutch investigators say that being too active is what is most likely to lead to depression. The results of an eight year study shows that a busy thyroid in seniors can lead to an increased risk for depression. It was already known that an extremely overactive (hyperthyroidism) or a markedly underactive (hypothyroidism) thyroid was connected to mental health conditions. The thyroid gland, located in the neck, produces hormones that govern metabolism and balances the body\u2019s reactivity with other hormones. Thyroid activity is stimulated by TSH (thyroid stimulating hormone) sent out from the pituitary gland. Therefore, if you measure the amount of TSH you can get a pretty good handle on the activity level of the thyroid. More TSH equals a busy thyroid; less TSH indicates a more sluggish thyroid. Researchers from the Erasmus Medical Center in Rotterdam, the Netherlands, measured the TSH of 1,503 older adults. The average age of the study participants was 70 years. Investigators used questionnaires to find out how subjects were feeling and used them to assess for depression. The subjects did not exhibit signs of depression during the initial interview, but did so over the eight year course of investigation. Participants were placed in one of three groups according to their TSH levels. Investigators then compared TSH levels against symptoms of depression. They found that the more active the person\u2019s thyroid, the more likely it was that they would develop symptoms of depression. People with the most active thyroids experienced the strongest symptoms of depression. Dr. Marco Medici was a co-author for the study. He said that these findings were new insofar as they revealed that older people whose thyroid was operating on the upper end of normal range had a notably higher risk for depression versus people with less active thyroid that was still in normal range. Medici said that the data indicates that even minute changes in thyroid activity and functionality could make a person vulnerable to some of the same mental health impacts as people diagnosed with hyper or hypothyroidism. The study holds implications for treatment of thyroid and for treatment of depression. Measuring TSH could become part of depression testing and regulating TSH might become part of treatment for depression. Patients with mild hyper or hypothyroidism could be made aware of their risk for depression and be given tools for combating this unpleasant side effect. This is one instance where slowing down with age is a good thing.